In a method for operating an internal combustion engine described in published German patent document DE 102 27 279, a pressure sensor which detects the pressure in a cylinder (guide cylinder) of the engine is associated with this cylinder. Furthermore, the engine has a structure-borne noise sensor, which indirectly detects the pressure changes in the individual cylinders. The pressure variation plays an important role in combustion control according to this known method: the agreement of the detected combustion chamber pressure with the combustion chamber pressure obtained from the signal of the structure-borne noise sensor is verified for the guide cylinder. If, during a certain period of time, the ascertained pressures differ by more than a certain value, an error message is output, which informs the engine's user of a certain wear condition.
An object of the present invention is to provide a method in which the engine performance quantities required for combustion control or regulation may be ascertained economically, yet precisely.